The construction of buildings from modular elements is an economic method of construction. Each module is prefabricated at a location away from the actual building site in an environment where construction conditions can be controlled and optimized. The modules are then transported to the building site. Assembly at the building site is faster and easier, since most of the on site construction work has been eliminated.
Modules may take a variety of forms. For example, a module may comprise a complete living or working space including a floor, a ceiling, and several walls. One module may encompass several rooms and may even include offset or stepped levels. However, the larger and more complex the module becomes, the more difficult it becomes to transport. Some modules comprise smaller elements, such as T- or H-shaped structural members which are assembled on site into living or working space. However, the smaller and more numerous the modular elements become, the greater the time and labor required at the building site becomes.
One problematic area in modular construction has been the design of efficient stairways. Since stairways function as connectors between levels in a building, it is difficult to incorporate an efficient stairway design into compactly designed modules which themselves occupy only a single level. One approach has been to design a single module with multiple offset levels and short stairways built integrally into the module to connect the levels. Another approach has been to form the stairway itself as an integral prefabricated member, generally of concrete. However, these approaches generally increase the complexity and have not proven to be cost effective. In addition, larger multilevel modules can be difficult to transport due to their larger size. Also, these designs have not made the optimal use of space, an important component in modular design. This is particularly a problem in buildings which must have two separate stairways accessing each level for fire safety. Generally, the two stairways are located in remote areas of the building.